Apparatus for handling liquid suspensions



June 7, 1949. D. B. WICKER ET AL APPARATUS FOR HANDLING LIQUIDSUSPENSIONS Filed April 4, 1944 2 Sheets-Sheet 1 NVENTORS. @Q/u, 62

ATTORNEY June 7, 1949. D. B. WICKER ET AL v I APPARATUS FOR HANDLING LIQUI D SUSPE'NSIONS Filed April 4, 1944 2 SheetsSheet 2 v HgV/ENTORS.

. BY fi e WM ATTORNEY Patented June 7, 1949 APPARATUS FOR HANDL INGLIQUID SUSPENSIONS Dan B. Wicker, Dunbar, and Charles W. Cox, St.

Albans, W. Va., assignors Corporation, Wilmington,

Delaware to American Viscose Del., a corporation of Application April 4,1944, Serial No. 529,540

1 Claim.

This invention relates to means for handling liquid suspensions ofparticulate materials, and more particularly to means for handlingliquid suspensions of textile staple fibers.

In withdrawing liquids from suspensions of particulate materialsit is acommon practice to apply vacuum beneath layers of the suspensiondistributed on the surface of a so-called vacuum table, the vacuumserving to draw the liquid downwardly from the material at a rapid rate.The vacuum table consists of a horizontally disposed circular tablehaving a liquid-perviou annular deck provided with side walls, and beingrotatably mounted above closed chambers which lead separately-to theports of a circular valve through which vacuum is applied or liquidwithdrawn. It is extremely difficult to deposit liquid suspensions ofparticulate materials on the rotating surface of the vacuum table in theform of a continuous blanket of uniform thickness and densitythroughout, due to the annular shape of the surface and the consequentdifference in linear velocity between the inner and outer portionsthereof. However, such uniformity is essential, especially when theparticulate material comprises textile fibers, to insure that all of thefibers will be equally treated.

It is, therefore, an object of the present invention to provide a novelmeans for depositing a liquid suspension of textile staple fibers or thelike on the annular liquid-pervious deck of a, conventional rotatingvacuum table, either in the direction ofrotation of the table, or inreverse direction thereto, and, in any case, in the form of a blanket orlayer of uniform thickness and density. It i another object of theinvention to facilitate the continuous removal of a mass of textilefibers or the like from such a vacuum table after liquid has beenwithdrawn therefrom.

These and other objects are accomplished by providing a novel troughhaving a delivery lip or edge such that the material is deposited oneach annular subdivision of the deck of the rotating vacuum table in anamount directly proportional to the relative linear velocity thereof.

- In the drawings,

, 2 Figure 7 illustrates a graphical method of designin an embodiment ofthe invention.

Referring more particularly to Figures 1 and 2,

the numeral 2 indicates a conventional vacuum' table having an innerannular periphery 3 :de-

fining a central portion d and an outer annular periphery 5, and mountedon a spindle or the like (not shown) for rotation in counterclockwisedirection above a plurality of closed chambers Ill, which lead to acircular valve provided with suitable connections to vacuum lines anddischarge receivers (not shown). The inner and outer annular peripheriesof table '2 define the limits of a liquid-pervious deck 6 having ablanket or layer of a liquidsuspension of textile staple fibers Ideposited thereon from trough 8 which is inclined at a slight angle withrespect to table 2. Pipes 9 positioned above deck 6 are provided with aplurality of spray heads l2, from which the same or different liquidsmay be applied to the fibrous blanket on deck 6 at predetermined pointsduring rotation of the table, if desired.

An endless belt l3 having spikes or prongs l4 thereon is positioneddirectly over deck 6 and is driven by pulleys l5 and It in the directionindicated by the arrows, so that the spikes or prongs l4 engage blanketI and lift it from deck 6 after table 2 has mad almost one completerev-- olution. A dOffil'lg roll I! is provided with flaps Figure 1 is aplan view of a device according t the invention;

Figure 2 is an elevational sectional view of the device shown in Figure1, one element thereof i8 which brush the fibers off belt l3 into chuteI9 through which they are delivered to container 20.

A dofiing roll 21 having spikes 22 thereon may also be provided adjacentbelt l3, to catch any fibers which may cling to deck 6, or whichaccidentally pass under belt l3, and to deliver such fibers to a pointwhere they will be engaged by spikes I4 on belt I3 and removed tocontainer 20. Trough 8 for depositing the liquid suspension in uniformlythick layers upon deck 6 of table 2 comprises two side walls 23 and 24and a plane bottom 25, as shown more clearly in Figure 2, and may beprovided with cross-baffles 26 and 2'! (Fig. 2) to insure evendistribution of the suspension across the entire width of the trough.Trough 8 is provided with a delivery lip or edge '28, the termini ofwhich, regardless of the relative widths of trough 8 and deck 6,substantially coincide with the inner and outer peripheries of the deck,and which, when the trough is projected on the table, substantiallydefines an arc of a circle, so that when the liquid suspension flowsthrough the trough at a fixed rate and table 2 is rotatedat a fixedrate, the portion of the flowing sheet of the liquid suspension which isdeposited upon any particular narrow annular subdivision of the 3 deckis directly proportional to the relative linear velocity of thatparticular narrow annular subdivision. Thus the amount of the suspensiondeposited upon the inner portion of the rotating surface is less thanthe amount deposited on the outer portionthereof, so'that thelinearvelocity differential between such rotating portions is compensated for,the weight of the suspension deposited per unit of annular surface isconstant, and the blanket or layer of material laid upon the surface iscontinuous and of uniform thickness and density throughout.

The projection of the relivery lip oredge 28 of trough 8 on the tablemay be regardeduas defining substantially an arc ofranimaginary circle,the locus of the center of which lies at some point on the surface ofthe deck on a radial line through the center of the table 'atarightangle to the longitudinal axis of the trough,'the distance of suchlocus from the center of the table being dependent upon the width of thetrough, and the width of the particular annular surface to which thetrough delivers. The distance of the locus of the center ofthetcirclewhich defines the trough lip, from: the center of the table, may bedetermined by dividing the difierence between the squares of the-greaterand smaller radii of the table by twice the width. of the trough. .Thegi'eater'radius of the table is measured from the center of the tableto' theannular periphery'fi, and the'smaller radius-ismeasured from thecenter of the table to annular. periphery 3. From these relationships,the shape of the lip can be determined mathematically.

As seen more particularlyin Figures 3 to"? inclusive, the width of thetrough may .be the same 'as that of the annular-deck, or it may begreater or less than thelatter. 'In all cases the projection of thetermini of the .arcforming the lipupon the table substantially.coincideswith the innerandtheouter periphery of the annular surface, and theprojected arc is not greater than .a. semi-circle. Thus, for example,when trough 8 is of the same vwidthas annular deck 8, and is positionedso that its edgesaretangential to the peripheries.ofthedeckfi, thelocusof the center of the imaginary-circleprojected from the lip lies onthe Y axis atapoint.,midwaybetween the inner and outer peripheries 3'and50f deck 6, and the arc is a semicircle,..as shown in Figure 3.

In Figure 4, the widthofitrough 8 is less than the width of annulardeclc fi-sand the trough is spaced away from the -X axisand positionedsothat neither of its edges is tangential tothe peripheries of deck 6, Inthat. case, the locus vof the center of the imaginary circleiprojectedfrom the lip lies on a radial line-extending at a right angle to thelongitudinal axis of. the trough (Y axis) at a point close to the outerperiphery of the deck, as shown at 30,-and the arc is less than asemi-circle.

In .the combinationillustrated in Figure. 5, the width of trough 8 isgreater than-the-width of deck 6, and the troughis epositioned so thatone ofits edges coincides with theX axis, and the other is tangential tothe outer periphery of the deck. There, the .locus' of the center of.the imaginary circle projectedzfrom the lip lies on a radial lineextending at a rightangle. to the longitudinal axis of the trough (Yaxis) at a' point closev to the inner periphery of the deck, and the arcis less than a semi-circle.

Figure 6 illustrates a combination in which the width of trough 8 isthe.- sameas that of. deck 6,

but the trough'iis positioned-so .that. neither .of-

:required 'lipzempirically, by a graphical procedure illustrated by thefollowing discussion:

.In order to effectually deposit the material from trough 8 evenly anduniformly upon annular deckii, any portion of the trough, extendingfrom, and having a-width W as measured from, that side of the troughwhich delivers to the annularportion of annular deck 6 nearest the.inner.=annular periphery 3 of table 2, should deliver to a portion ofsuch deck defined by the inner periphery 3 and an imaginary concentricouter circle having a radius RtIlE-tedin accordance .with' the equation:

(Ra -R0 where R0 is the inside radius. ofthe annular deck-6; and

K is a factor which is determined for any given system by the insideandoutside radii 'of deck'fiand the overall channel width of troughB.

When the widthoftrough' 8' and the inside and outside radii of deckifion tablej2'are' known; the numerical value of K may .be. found bysubstituting these known values in the above equation.

'Thenthe annular de'ck'may be 'divided into a series of annular portionsby marking'oif'a series. of points each. spaced, at .any arbitrarilyselected progressively greater distance from the center of the tableandtintersectingeach of the series 'of points .so, marked ofi" with acircle. Then the value .of the radiusyof'the'outer circle defining each"portion .is substituted for Rt in the equation, and a valueof'W' issolved for each substitution. Then .ptheitrou'gh is divided intoparallel, longitudinally extending strips between imaginary lines'spaced;fromthat edge of the trough which extends to apoint above theinside periphery of the annular surfacedistances corresponding to thevaluesof Wbbtained. The intersections of vertical planes through the;parallel imaginary lines with the imaginary concentriccircles determinelociwhich define the arc of the trough lip. ,A' scale drawingshowing thetrough approaching the tableat the desired angle maybe prepared, showingthe trough-widths as lines parallel to the sides of the trough, and thedeck'widths as concentric circles, the intersection of eachparallel linewith its-corresponding circle defining the projection of the deliverylip or edge 28 of each trough width'on the table As an-illustration, letit be'assumedthat a vacuum table Ihas adiameterof 12 feet, andthecentral-portion thereof has a diameter-of 4 feet (Ro=2 feet) while theinside-width-of trough a is'-.3. -feet. 'In'that case,=.the'numericalivalueiof K is 10.67, .as determinedbyzssubstituting'z'thevalues of 6, 2, and 3 for Rt, Ro, andrwrespectively inthezeguation:

Using this valuev of Kyprogressively larger widths W of the:trou'ghrllistedzin .the;.table below) man She: determined"forrprogressively larger arbitrarily selected annularzaporticnsinfdeck=:5

A mass of textile fibers, such as a mass of artificial staple fiberscomprising regenerated cellulose which has been subjected to treatmentwith Water or aqueous media, and which is suspended in such liquidmedium, may be continuously deposited from a trough having a speciallyconstructed delivery edge according to our invention, in even anduniform layers upon the liquidpervious deck of a rotating vacuum table,and when vacuum is applied in the usual manner the liquid is rapidly andefiiciently withdrawn downwardly from all of the fibers constituting themass. If desired the mass of fibers thus uniformly deposited on the deckmay be subjected to further treatment thereon, such as, for example,washing to remove residual spinning bath, desulfurizing and removal ofdesulfurizing agent, bleaching and removal of bleaching agent, or totreatment with appropriate conditioning agents, such as softeningagents, lubricating agents, etc., to render the fibers more amenable tofurther textile processing, such as carding, spinning, etc., whichtreatments may be carried out in sequence at predetermined segmentalintervals of rotation of table 2. Due to the even distribution of themass of fibers on the annular deck, when vacuum is applied below thedeck in the usual manner, the treating liquid which has been sprayed orshowered upon the fibers is drawn downwardly through the mass at a rapidand uniform rate and penetrates all of the fibers equally, with theresult that fibers having uniform properties are obtained. After theliquid has been withdrawn, the blanket or layer of fibers may becontinuously removed from the table and sent to a suitable container orthe like, as previously described herein.

Although the invention has been shown and described with more particularreference to use thereof in connection with liquid suspensions oftextile staple fibers, it will be apparent that the novel trough may beused whenever it is desired to deposit even, uniform layers of liquidsuspensions of particulate material on a rotating annular surface forany purpose.

We claim:

In an apparatus which comprises a rotating foraminous annular surfacedisposed in a horizontal plane and a trough inclined from the verticalfor depositing a liquid suspension of particulate material thereupon sothat the amount of suspension deposited on any given unit width of theannular surface is directly proportional to the relative linear velocityof such unit, said trough having a delivery edge the projection of whichon the annular surface effectively defines substantially an arc of acircle and the locus of the center of which circle lies on the annularsurface on a radial line through the center of said surface extending ata right angle to the longitudinal axis of the trough, and the termini ofwhich are coincide with the inner and outer peripheries of the annularsurface, the locus of points on said are being ascertainable from theequation (Rt -Ro =K W (where R0 is the inside radius of the annularsurface and K is a factor determinable by substituting in th equationthe outside radius of the annular surface for R4; and the width of thetrough for W) by dividing the width of the annular surface into a numberof portions between imaginary concentric circles and substituting thevalue of the radius of the outer circle defining each portion for Rt insaid equation, solving for W, and dividing the trough into parallel,longitudinally extending strips between imaginary lines spaced from thatedge of the trough which extends to a point above the inside peripheryof the annular surface distances corresponding to the values of Wobtained, the intersections between the imaginary concentric circles andvertical planes through said parallel imaginary lines constituting theloci defining the arc,

DAN B. WICKER. CHARLES W. COX.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 736,215 Chapman et al. Aug. 11,1903 768,094 Turner Aug. 23, 1904 1,335,695 Oliver Mar. 20, 19201,772,684 Pink Aug. 12, 1930 1,776,568 ONeale Sept. 23, 1930 1,887,587Ekeberg Nov. 15, 1932 2,219,954 Geiger Oct. 29, 1940

